Cam type retractable mechanisms



Dec. 23, 1958 J. MARCOTTE CAM TYPE RETRACTABLE MECHANISMS 2 Sheets$heet1 Filed Aug. 17, 1953 m y Ll, %w a i 1;

Dec. 23, 1958 J. L. MARCOTTE CAM TYPE RETRACTABLE MECHANISMS 2Sheets-Sheet 2 Filed Aug. 17. 1953 N m M Feb-mag! peda /an JNVENTORLKIM/IE5 L. MAQco'r ATTORNEY- United States Patent CAM TYPE RETRACTABLEMECHANISMS James L. Marcotte, Lawndale, Califl, assignor, by mesneassignments, to Paper Mate of Puerto Rico, Inc., Salinas, Puerto Rico, acorporation of Puerto Rico Application August 17, 1953, Serial No.374,497

17 Claims. (Cl. 12042.03)

This invention relates to writing implements of the ball point type andhas to do more specifically with a novel projecting-retracting mechanismwhereby the writing point of such implements may alternately beprojected out of and retracted back into the implement.

Ball point writing implements, as manufactured heretofore, normallyemploy a replaceable cartridge comprising a tubular ink reservoir and awriting tip assembly carried by one end of such reservoir, the writingtip assembly including a rotatable ball which picks up ink supplied fromthe reservoir and then deposits such ink from the surface of the ballonto the surface upon which the ball is rolled during the writingoperation. The small size and long life and large ink supply of thesepens are an important and valuable characteristic. Most prior attemptsto make ball point pens with a retactable point (to thereby facilitatecarrying of the pen without staining garments with ink from the point,and without the use of a removable cap on the pen) necessitated the useof a shorter cartridge, the reduction in length being caused by thecomplexity and extent of mechanism employed for selectively projectingand retracting the writing tip. The use of a standard or normalcartridge was not feasible because its length plus the space occupied bymost prior retracting mechanisms rendered the instrument excessivelylarge and long. The reduction in length was obtained at the expense ofthe tubular ink reservoir, thereby reducing its capacity and the writinglife of the pen.

Since most manufacturers desire to make non-retractable and retractablepens, it was necessary to carry at least two styles of cartridges:dealers had to carry two styles of refill or replacement cartridges instock, and many instances of confusion were bound to arise by selling arefill cartridge of improper length for the customers pen.Manufacturing, shipping and selling difficulties were thus encountered.

The present invention permits the use of cartridges of normal orstandard length (as used in non-retractable pens) in a pen body whichis'no larger and embodies an efficient, selectively operable retractingand projecting mechanism which is self-locking.

One of the objects of my invention is to provide in a ball point pen aprojecting-retracting mechanism of simple and rugged construction whichis economical to manufacture and unlikely to get out of order.

Another object is to provide a writing implement of the type describedwhich is composed of a minimum number of parts, which parts are ofsimple and sturdy design and are easy to assemble and disassemble.

It is another object to provide such a mechanism which is easy tooperate, positive and dependable in operation, inherently incapable ofjamming or binding, and capable of withstanding a large number ofoperations without failure.

It is a further object of the invention to provide such a mechanism,wherein a writing unit is held in an extended or in a retracted positionwithout a separate latching mem- 2,865,331 Patented Dec. 23, 1958 berand wherein no independent latching means is required.

It is a further object of the invention to provide a writing implementof an improved construction so that nonmetallic materials such assuitable plastics may be used for the construction of almost the entiredevice.

The invention may be further characterized as a mechanism whichincorporates camming means associated with an operating plunger, and acam follower associated with the upper end of a writing unit, whichco-act upon successive depressions of the operating plunger to impartaxial and lateral motion to the writing cartridge and thus extend andhold the writing tip in extended position and retract and hold the tipin retracted position at the will of the operator.

These and other objects, advantages, and particular characteristics ofthe invention will become apparent from the following description andaccompanying drawings in which:

Fig. 1 is an enlarged longitudinal sectional view of one exemplary formof retractable writing instrument, with the tip in projecting position.

Fig. 2 is an enlarged longitudinal section of the upper body.

Fig. 3 is a fragmentary longitudinal sectional view similar to Fig. 2,showing a depressed position of the pronged plunger when retraction isinitiated.

Fig. 4 is a view similar to Fig. 3, showing the position of the parts aninstant later than that illustrated in Fig. 3.

Fig. 5 is a transverse section taken along plane VV of Fig. 2.

Fig. 6 is an enlarged longitudinal section similar to Fig. 2,illustrating a fully retracted position of the cartridge.

Fig. 7 is an enlarged longitudinal section taken along the line VII-VIIof Fig. 5, showing the position of the pronged plunger and the camfollower immediately following a successive depression of the operatingplunger to initiate projection of the cartridge.

Fig. 8 is a longitudinal section taken along plane VIHVIII of Fig. 5,illustrating movement of parts from the position shown in Fig. 7, towardproject position.

Fig. 9 is a diagrammatic representation showing a sequence of variouspositions A to F of the cam follower during the sequential operationillustrated in Figs. 1-8; and

Fig. 10 is a longitudinal sectional view of the upper body of a writingimplement, showing another modification of the invention.

Generally stated, the exemplary writing instrument illustrated in thedrawings consists of a shell or housing containing a writing cartridgeand operating means whereby the cartridge may be selectively moved froma projected position to a retracted position and vice versa, thecartridge being inclined to one side of the axis of the instrument whenin projected position, and being inclined to the opposite side of theaxis when in retracted position. This new mode of operation isaccomplished by novel and simple means, and permits the use of long,

high capacity cartridges. In order to facilitate understanding, theessential elements comprise a cam follower tip carried by the upper endof an ink cartridge within the barrel of a writing instrument, a fixedbody element within the barrel, said body element having a downwardlydirected face provided with two adjacent means for receiving the camfollower tip, and a pair of oppositely inclined surfaces, each suchinclined surface being inclined toward only one of said follower tipreceiving means, and a camming means connected to an actuating plungerand movable through the body element into contact with the cam followertip to move such tip into an inclined surface which then guides thefollower tip to the other follower tip receiving means. When thefollower tip is at one of-saidtip receiving means the cartridge is inwriting position and when the follower tip is at the other receivingmeans the cartridge is in retracted position.

The exemplary retractable writing instrument illustrated includes awriting cartridge 11 which is shown as a cylindrical ball point pen unithaving an upper, tubular ink reservoir portion 12 and alowcr writing tip13 of reduced diameter. The 'c-artridge'll is slidably positioned in alongitudinally extending bore or chamber of a lower case '14-and anupper.body element '15, the latter being permanently encased in a shell "16.It isbiased toward a retracted position and into operating engagementwith an upwardly directed cam follower '17 by a retracting spring 18,which bears against a retaining shoulder 19 provided in the lowerportion of the case 14 and a shoulder or projection of'the cartridge. Asclearly shown in Fig. 2, the cam follower 17, which is movably butpermanently retained within the body element 15, has an upwardlydirected tip '21and a lower cap portion 22, to loosely fit over theupper end of the cartridge and thereby permit lateral motion of the camfollower.

The longitudinally extending chamber 20 in the body portion 15 isadapted to loosely receive the cartridge 11 so that the-cartridge maymove laterally as well as longitudinally. The upper end of the body 15is provided with an enlarged chamber 23 in which the cam follower 17 ismovably retained. The diameter of the cap 22 of the carnfollower 17 isslightly larger than the bore 20. The upper and enlarged chamberj23contains a stationary body element 24, this element forming the upperend of the chamber 23 and being held in position by a press fit and.

the constricting action of the outer shell 16. Body elements 15 and 24can therefore be considered as a unit.

Mounted within the shell 16 above intermediate body portion 24 is anoperating plunger'25 which includes an operating button 26 extendingaxially of the pen through a port in the shell and camming means shownin the form of-two downwardly directed parallel and adjacent prongs, aretracting prong '28 and a projecting prong 29. The prongs or 'cammingmeans forming the inner end of the plunger are longitudinally butnon-rotatably slidable in the adjacent bores 30 and 31 which jointlyconstitute aperture means extending through the stationary body portion24 and communicating with chamber 23 and lower face/36 of the body 24.The plunger is biased upwardly by spring 32 resting on the body portion24 and is retained within the ,shell 16 by a stop shoulder 27 carried bythe plunger and bearing against the inner surface of the shell. It willbe noted that prong 28 and bore '30 are on one side of the axis of theinstrument, whereas prong 29 and its bore 31 are on another, 0ppositeside of the axis.

It will be noted that the rounded tip of the cam follower is received intip-receiving bore 30 when the cartridge is in writing position (Fig. l)and such earn follower tip is received in tip-receiving bore 31 when thecartridge is in retracted position ('Fig. 6 Body portion 24 is providedwith a downwardly facing project position shoulder or holding means 34against which the end of cartridge 11 or its cam follower cap may rest(as shown in Fig. 2) and a retract-position face 36 against which theendofcartridge 11 or its cam follower cap may rest (as shown in Fig. 6).This shoulder 34 and face '36 form a part of the body and an upper endof enlarged chamber 23 which movably retains the cam follower 17. Itmaybe noted that the Project position shoulder 34 is formed adjacent toand radially away from the retracting prong 28 and its bore 30. Shoulder34 lies in a plane spaced from face 36 a-distance adequate to cause thewriting tip of the cartridge to be moved .or

-displacedlongi udinally a-sui abledi ta e- The length f m foll wer t p1 i sl ght y gr er than the distance separating the transverse planes ofshoulder 34 and face 36.

The operating means for moving the cam follower and cartridgelongitudinally and laterally'comprise the prongs 28 and 29, a camfollower 17 (or its tip 21) and inclined surfaces which guide the upperend of the cartridge (through the cam follower or a tip) from projectedto retracted position and vice versa. The detailed means shown in theexemplary drawings include camming means or surfaces formed in the endsof prongs 28 and 29. .Retracting prong 28 is provided with an inclined,preferably concave camming surface 38 and projecting prong 29 isprovided with an oppositely in=clined,. preferably concave cammingsurface 39. These carnming surfaces are adapted to contact and impartdirectionalmovement to tip 21 of cam follower 17.

Adjacent the lower opening of the bores or apertures 3t and 31, face 36of the body portion 24 is Provided with two transversely extending,oppositely inclined surfaces, herein referred to as a retracting incline48 and a projecting incline 4-9. These inclines are preferably concavedto receive and guide the end of tip 21. Retracting incline 48 is wellshown in Fig. 2 and leadsfrom a position adjacent bore30 into bore 31.It is inclined 'or descends toward bore 31 so that end of tip 21, whenfirst received into'the incline from bore 30, would be urged (byretracting spring 18) to slide alongthe incline toward and enter bore31.

The prong 28 has been referred to as .a retracting prong since itcontacts the tip '21 of the cam follower 17 on the retracting depressionof the operating button and the camming surface 38 moves said tip ontoretracting incline 48. The prong 29 has been referred to as a projectingprong since .it contacts the tip 21 of the cam follower 17 on theprojecting depression of the operating button and the camrning surface39 moves tip 21 from a position in bore 31 onto projecting incline 49leading back to bore 30. However, it is to be noted that the bore 31) inwhich the retracting prong 28 moves can be more properly referred to asa project-position bore, because the tip 21 of the cam follower 17 movesinto this bore when the writing tip of the cartridge is projected, andthe bore 31 can be more properly referred to as a retract-position bore,because the tip 21 of the cam follower 17 moves into this bore when thewriting unit is retracted. Finally, the retracting incline 48 has beenso designated because its inclined surface leads into theretract-position bore 31, and the projecting incline 49 has been sodesignated because its inclined surface leads or descends into theproject-position bore 30.

The operation of my retractable writing instrument will now bedescribed, starting with the writing unit 11 in its normal projectedwriting position, as clearly shown in Fig. 2. In this position thewriting unit 11 is held projected against the retracting influence ofthe spring 18, because the upper face of the cap 22 of the cam follower17 is in engagement with the project-position shoulder 34 of the bodyelement 15, and the tip 21 of the cam follower 17 is partly within theproject-position bore 30.

When the operating button 26 is depressed to retract the writing unit11, the plunger 25 moves downward to cause the retracting prong 28 tocontact the tip 21 of the cam follower 17 and urge the writing unit 11axially downward. The axial movement is continued until the prong 28 hascarried the tip 21 to the level of the lower opening of the projectposition bore 30. This position of the parts is shown in Fig. 3.

Fig. 4- shows the parts an instant later when with the furtherdepression of the operating button 26 the tip .21 of the cam follower'17, under the influence-of the spring 18, has been carried by or cammedlaterally by the retracting cam surface 38 of the prong'23 and onto arelatively high point of the adjacent retracting incline .48.

Tip v21 tends to move 'down the incline toward bore 31 (being urged byretracting spring 18.) but as long as plunger .25 isdepressed the tipwill not enter here 31 because the cylindrical side of the prong 29 iscontacting the cylindrical side of the tip 21.

However, (when the operating button 26 is released the plunger 25 andthe prong 29 move axially upward under the restoring action of thespring 32, and as the prong 29 is withdrawn back into the bore 31, thetip 21 of the cam follower 17 is freed and under the influence of thespring 18 is caused to cam on the retracting incline 48 and into theretract-position bore 31, and move axially upward within the bore, untilthe upper face of the cap 22 of the cam follower 17 engages theretractposition face 36. When the parts are so positioned, as shown inFig. 6, the writing until 11 is fully retracted.

The above-described retracting sequence of operation is furtherelucidated schematically in the diagrams A-B--C--'D of Fig. 9, themovement of the tip 21 being shown from writing position (projectedposition) as in diagram A onto incline 48 (diagram B), along the inclinetoward bore 31 (diagram C) and into retracted position wherein the tipis in bore or aperture 31 (diagram D). It is to be understood that theaxial and lateral motions of tip 21 are transmitted by the tip, throughthe cap 22 of the cam follower to the upper end of the cartridge. Theinclined camrnin surfaces form a unit-directional path for the camfollower.

When the operating button 26 is again depressed with the parts in thepositions shown in Fig. 6, the plunger 25 moves downward to cause theprojecting prong 29 to contact the tip 21 of the cam follower 17 andurge the writing unit 11 axially downward. The axial movement iscontinued until the prong 29 has carried the tip 21 to the level of thelower opening of the retract position bore 31. This position of theparts is shown in Fig. 7, a section taken along a broken plane VIL-VIIof Fig. 5.

Fig. 8 shows the parts an instant later when with the further depressionof the operating button 26 the tip 21 of the cam follower 17, under theinfluence of the spring 18, has been cammed by the projecting camsurface 39 of the prong 29 and on to a relatively high point of theprojecting incline 49. As is clear from the figure, the tip 21 will beheld in this position as long as the plunger 25 is so depressed becausethe cylindrical side of the prong 28 is contacting the cylindrical sideof the tip 21.

Now when the operating button 26 is released, the plunger 25 and theprong 29 move axially upward under the restoring action of the spring32, and as the prong 28 is withdrawn back into the bore 34), the tip 21of the cam follower 17 is freed and under the influence of the spring 18is caused to cam onto the projecting incline 49 and into the projectposition bore 30. Movement of tip 21 along incline 49 moves the upperportion of cartridge 11 laterally, such lateral movement ceasing whentip 21 engages bore 30. Such lateral movement in the device illustratedalso places the cap 22 under the shoulder 34.

' moved laterally from one lateral position wherein the writing unit wasretracted to another lateral position wherein the writing unit wasprojected, an axial movement occurring simultaneously with the lateralmovement, the axial movement being limited by longitudinally displacedportions of the stationary body member.

The above-described projecting sequence of operation is furtherelucidated schematically in the diagrams D-E-F-A of Fig. 9. Diagram Dshows tip 21 within bore 31, such tip being moved onto incline 49 indiagram E, moving along the incline in diagram F and into projected orwriting position in diagram A.

Thus, if the. writing tip is projecting, depression and release of thebutton effects retraction of the writing tip whereas if the writing unitis retracted, similar depression and release of the button causes thewriting unit to be projected.

When a cam follower such as 17 is used in the body of the pen, astandard, open-ended cartridge can be used as a refill. The operatingmechanism is extremely compact and maximum ink capacity can be used in apen of short external length. By making the axial bore 20 larger (asindicated at 20 in the modification shown in Fig. 10) so as to permitgreater lateral movement to the cartridge, body 15 and portion 24' canbe made as a single unit and the cartridge -11' may have its upper endprovided with a tip or cam follower 21' which is attached to thecartridge or made an. integral part thereof before the cartridge isinserted into the instrument. Portions of the species of body member15', illustrated in Fig. 10, which are counterparts of portions of theearlier described species of body member 15, have been designated bysimilar but primed reference numerals; namely, face 36', shoulder 34,bore 31, and bore 30'. The operation of the pen is substantiallyidentical to that described hereinabove.

It is to be understood that various changes and modifications may bemade without departing from the inventive concepts here disclosed, sincethe drawings illustrate but an example and details of construction maybe varied.

I claim:

1. In a writing instrument including a writing cartridge having adownwardly directed writing tip, the provision of: a plunger providedwith a pair of downwardly directed prongs; a body element including twolongitudinally extending, parallel bores adapted to slidably receive theprongs of the plunger, said bores being on opposite sides of the axis ofthe instrument, said body element having a downwardly directedproject-position shoulder adjacent one of said bores, a retract-positionface, and a pair of inclined surfaces in such face, each one of saidpair leading to and being inclined in the direction of a respective oneof said bores, said surfaces: being oppositely inclined; an upwardlydirected cam follower adapted tocontact said surfaces and partly entersaid bores, said cam follower being in operative engagement with theupper end of a writing cartridge; and camming means carried by the endof each of said prongs to impart axial motion along one of said boresand lateral motion along one of said transversely extending, inclinedsurfaces to the cam follower and the upper end of the writing cartridgeupon axial movement of the plunger.

2. A Writing instrument of the character stated in claim I 1, whereineach of said inclined surfaces extends from adjacent one of the bores.

3. A writing instrument as stated in claim 1, wherein each of theinclined surfaces is concaved to receive and guide an end of the camfollower.

4. A writing instrument of the character stated in claim 1, wherein thecam follower is connected to the upper end of the cartridge.

5. A writing instrument of the character stated in claim 1, wherein thecam follower is movably retained in the writing instrument, and has acap portion adapted to receive the upper end of a cartridge.

6. In a writing instrument including a barrel having a writing tipaperture at its lower end, and containing a laterally and axiallymovable ink cartridge having a writing tip adapted to project throughthe writing tip aperture when in writing position, and a spring normallybiasing the cartridge and writing tip into retracted position, the combination of: a cam follower having an upwardly directed rounded endcarried by the end of the cartridge within the barrel; a stationary bodyelement provided with a downwardly directed face and adjacent boresextending through 7 said element and in, communication with said face,said adjacent bores being adapted to receive the upwardly directedrounded end of the cam follower; said body element being furtherprovided with guiding surfaces formed in saidjface and inclined in thedirection of a respective one of said bores to facilitate movement ofthe cam follower end from one bore to another; and camming meansincluding adjacent prongs provided with camming surfaces, each of saidprongs being slidably mounted in a respective, one of said adjacentbores into contact with said cam follower end to eject it from a boreand direct it onto a guiding surface leading to the adjacent bore.

7. In a writing instrument as stated in claim 6, wherein the: guidingsurfaces in said face are two in number, said guiding surfaces beingoppositely inclined and such guiding surfaces being on opposite sides ofsaid adjacent bores.

8. In a writing instrument as stated in claim 6, wherein the guidingsurfaces are two in number, said guiding surfaces being oppositelyinclined and concaved and on opposite sides of said adjacent bores, andthe camming surfaces of the camming means are oppositely inclined.

9. In a writing instrument as stated in claim 6, wherein the cammingmeans are connected to a plunger extending from the barrel and theguiding surfaces provided in the face are two in number, said guidingsurfaces being oppositely inclined and concaved and on opposite sides ofsaid adjacent bores, and the camming surfaces of the camming means areoppositely inclined.

10. In a retract-project mechanism for a writing instrument including abarrel having a writing tip aperture at its lower end, an ink cartridgehaving a writing tip adapted to project through the writing tip aperturewhen in writing position, a spring normally biasing said cartridge andwriting tip into retracted position, and an outwardly biased plungerextending from the upper end of the barrel, the combination of: a camfollower adapted to be carried by the end of an ink cartridge within thebarrel, said cam follower being provided with an upwardly directedrounded end; a stationary body element provided with a downwardlydirected face, said face being provided with two adjacent apertures forthe reception alternately of said upwardly directed rounded end of thecam follower; said body element having a face having inclined surfacesformed therein andleading to each of said cam follower end receivingapertures, said inclined surfaces being oppositely inclined and in thedirection of their respective apertures; and camming means, havingoppositely inclined camming surfaces, movable through said body elementinto contact with the rounded end of the cam follower when said camfollower is in one of said two cam follower end receiving apertures tomove the end of the follower onto an inclined surface leading to theother and adjacent follower end receiving aperture.

11. A writing instrument having an elongated tubular barrel, a writingcartridge slidable therein and provided with a writing tip atone endthereof and a laterally movable cam follower having an upwardly directedtip carried on the end of the cartridge opposite the writing tip, amechanism for shifting the cam follower from one tothe other of twolaterally spaced positions and selectively retaining the follower insuch position, including a stationary body element provided with adownwardly directed faceand aperture means formed in the body elementandcommunicating with said face, the face being piovided with two concaved,oppositely inclined surfaces, one on each side of the aperture means,said oppositely inclindedsurfaces constituting guiding surfaces tofacilitate movement of the cam follower tip from one of said laterallyspaced positions to the other; and camming me I movable longitudinallythrough the aperture means in th'e 'ody elernent and having oppositelyinclindedcarn; m1 sa d upisiii one or said positionsin theaperture meanstoniove the tip' from said one position onto the respective surfaces forcontactingjtheicam follower, tip when.

concaved, inclinded surfaces to guide the tip to. other position. v

12 A writing instrument as stated in claim 11 wherein the stationarybody element is provided with a holding means to engage and hold the camfollower in one of the lateral positions of the follower to prevent thecam follower tip from extending fully into the aperture means when thecam follower is in such lateral position.

13. A writing instrument as stated in claim 11 wherein the stationarybody element is provided with a laterally displaced holding means in aplane spaced from the face of the body element, said holding meansengaging and holding the follower when said. follower is in one of thelateral positions to hold the writing tip of the cartridge in writingposition.

14. A writing instrument having an elongated barrel, a writing cartridgeslidable therein and provided with a writing tip at one end thereof, acam follower adapted v to engage the end of the cartridge opposite thewriting tip, said follower having an upwardly directed tip laterallymovable within the barrel, a mechanism for shifting: the cam followerfrom one to the other of two laterally spaced positions and selectivelyretaining the follower in such position, including a stationary bodyelement provided with a downwardly directed face and aperture meansformed in the body element and communicating with said face, the facebeing provided with two oppositely inclined surfaces, one on each sideof the aperture means, said oppositely inclined surfaces constitutingguiding surfaces to facilitate movement of the cam follower tip from oneof said laterally spaced positions to the other; and camming meansmovable longitudinally through the aperture means in the body elementand having oppositely inclined, laterally disposed camming surfaces forcontacting the cam follower tip when said tip is in one of said lateralpositions to move the tip from said one position onto the respectiveinclined surfaces to guide the tip to the other lateral position.

15. A Writing instrument having an elongated barrel, :1 writingcartridge slidable therein and provided with a writing tip at one endthereof, a cam follower adapted to engage the end of the cartridgeopposite the writing tip, said follower having an upwardly directed tiplaterally movable within the barrel, a mechanism for shifting the camfollower from one to the other of two laterally spaced positions andselectively retaining the follower in such position, including astationary body element provided with a downwardly directed face andaperture means formed in the body element and communicating with saidface, the face being provided with two oppositely inclined surfaces, oneon each side of the aperture means, said oppositely inclined surfacesconstituting guiding surfaces to facilitate movement of the cam followertip from one of said laterally spaced positions to the other; a holdingmeans forming a part of the stationary body element for limitingmovement of the cam follower when said follower is in one of thelaterally spaced positions, at least part of said follower tip extendinginto the aperture means when the cam follower is in the other laterallyspaced position; and camming means movable longitudinally through theaperture means in the body element and having oppositely inclined,laterally disposed camming surfaces for contacting the cam follower tipwhen said tip is in one of said lateral positions to move the tip fromsaid one position onto the respective inclined surfaces to guide the tipto the other lateral position.

16. In a writing instrument having an elongated barrel adapted toreceive a writing cartridge for axial movement therein from and toprojected writing position and a retracted position and including aspring normally biasing the cartridge into retracted position, theprovisior of: a plunger, having an outer portion and an inner portion; acam. follower. adapted to engage the upper end of a writing cartridge inthe barrel; a stationary intermediate member within the'barrel, saidintermediate member being provided with aperture means extendingtherethrough to slidably but non-rotatably receive the inner end portionof the plunger for longitudinal reciprocation in said aperture means;said inner end portion having two laterally disposed camming meansinclined in opposite directions; said intermediate member being providedwith two oppositely inclined cam surfaces adjacent the aperture means,each of said cam surfaces sloping toward an opposite lateral side ofsaid aperture means; said cam surfaces defining a unidirectional campath for said cam follower whereby, by successive reciprocation of theplunger in said aperture means, said follower is engaged by and cammedby the camming means onto said cam surfaces in succession and laterallyshifted.

17. A writing instrument as stated in claim 16 wherein the stationaryintermediate member is formed with a holding means to limitlongitudinally directed movement of the cam follower when said followeris in one of the laterally spaced positions, said cam follower having 'atip extending into the aperture means when the cam follower is in theother laterally spaced position.

References Cited in the file of this patent UNITED STATES PATENTS

